[mike in idaho]

Im looking at my cams and trying to line up the index marks, and the only one that will let me line it up is my inlet cam. when the chain was connected i could rotate my generator and see where the exhaust cam index mark was and when you rotate it to access the master link the cam rotates and wont let me rotate the cam (with out chain) back to line up index mark. i understand that both cams need to me lined up. but the exhaust cam will not allow me to line it up, its on the other side of the cam??? is there a way to rotate the cam with out the chain connected?? any help guys would really be great. one of my buddies mentioned its possible my "shims" went out and thats why i was losing compression/power on my left cylinder.
also, i noticed that my valve adjusting lock nut seems to be froze to the middle adjusting screw, any tip on getting that free? simple lock eaze do the trick?

-scott

What shims?, your buddy must be thinking about a different engine(shim under bucket style). One way to make it easier to line up the camshaft timing marks is to back all the valve adjustments off completely first. That valve adjusting nut has probably been overtightened and the threads are deformed. Have somebody hold a box end wrench on the nut while you turn the adjuster screw (clockwise) to free it. Get a screwdriver big enough to properly fit the slot, so you don't damage the adjuster end, tap on the end of the screwdriver as you turn it. Toss the nut when it comes off and buy (4) new ones.

 

[XTOP20A]

just forget about using any marks to find correct cam position,you guys are way overthinking a super simple procedure
to adjust any set of valves on ANY 4 cycle engine:
first find tdc compression stroke,best/easiest just pull all sparkplugs
put you finger over the sparkplug hole,wrench over until you are well into compression
drop a soda straw in the plug hole and rotate to tdc
adjust all valves on that cylinder
repeat on the next cylinder
this is the proven idiot-proof method you cannot do it wrong this way

 

[koolio]

I may adopt your method.

drop a soda straw in the plug hole and rotate to tdc

Just don't understand this bit whatsoever, soda straw?

My LT marks and T marks do not correlate whatsoever to the TDC of either cylinder.

The cams are shaped like eggs cross sectionally, I set the position where the top of both eggs line up to the cam follower to press both exhaust and inlet valves down, this is when I measure each side.

If this is correct, I can't get a 0.05mm feeler gauge in between them so I guess it still must be set right at 0.03mm, not sure how to get such a flimsy thin gauge in between them anyhow.

 

[XTOP20A]

I may adopt your method.

drop a soda straw in the plug hole and rotate to tdc

Just don't understand this bit whatsoever, soda straw?

My LT marks and T marks do not correlate whatsoever to the TDC of either cylinder.

The cams are shaped like eggs cross sectionally, I set the position where the top of both eggs line up to the cam follower to press both exhaust and inlet valves down, this is when I measure each side.

If this is correct, I can't get a 0.05mm feeler gauge in between them so I guess it still must be set right at 0.03mm, not sure how to get such a flimsy thin gauge in between them anyhow.

it is not MY method but one that is common knowledge
:lol: what you are doing,that sounds about as excactly wrong as you can try to do it
the cams have a base circle this is where clearance is set
just use the method i described
the soda straw is simply used as a safe,visible gauge that rides on top of the piston and shows you EXCACTLY(close enuf to excactly) when you are at tdc(top dead center)

 

[koolio]

Thanks, the penny just dropped, compression with the finger means both valves are closing on that cylinder. Then you drop the straw in, and then which bit do I measure the valves at? Is it when the straw stops moving up anymore?

Genius really thanks for this, its been doing my head in for a couple of hours now.

 

[XTOP20A]

Thanks, the penny just dropped, compression with the finger means both valves are closing on that cylinder. Then you drop the straw in, and then which bit do I measure the valves at? Is it when the straw stops moving up anymore?

Genius really thanks for this, its been doing my head in for a couple of hours now.

woohoo !
the straw will stop upwards motion at tdc, then start to fall back down with the piston as you very slowly rotate the engine(best to always rotate in the same direction as running)
when the straw is at the top of its travel you are in the correct tdc zone for adjusting both valves on that cylinder

there is actually a very few degrees of crankshaft rotation where the piston pretty much "dwells" at tdc
this is a hole nother subject and gets heavy into things like connecting rod length

 

[koolio]

Just to update: I did the straw method and tdc is in indeed where the the top of the egg shaped cams press both valves in, so don't see how I was doing it wrong. although the straw method is superior and more accurate as I don't have to keep checking both inlet and exhaust sides by eye.

I can't get a 0.05mm feeler gauge in between them, so it must be set ok or at zero?

 

[XTOP20A]

Just to update: I did the straw method and tdc is in indeed where the the top of the egg shaped cams press both valves in, so don't see how I was doing it wrong. although the straw method is superior as I don't have to keep checking both inlet and exhaust sides by eye.

I can't get a 0.05mm feeler gauge in between them, so it must be set ok or at zero?

when you say both valves pressed in do you mean closed ?
the "egg" of the cam is called a lobe and it only presses the valve open,against spring pressure
when valves are closing the cam is not "pressing" them closed but only allowing the springs to return the valve to the closed,as the cam follower comes off the lobe and goes onto the base circle
.05mm = about .002" which i think all have said is a safe clearance

 

[mike in idaho]

The straw comes up on the exhaust stroke too(remember, two revolutions per combustion cycle), if both rockers are tight go around one more turn and feel for clearance again. One way to do it is watch the intake valve rocker, as you turn the engine. When you see the rocker/valve go down and start back up, the next time the straw is up is the spot to adjust the valves.

 

[koolio]

:roll: Honestly don't know whats wrong with me today, its like my brain isn't on or something.

Apologies you are absolutely right, the lobe opens the valves, for some reason I thought both lobes pressed down at the same time closing the valve, which I know cannot be the case, some serious amnesia going on today, in my defence its been 2 years since I set valves and that was on a single.

I must have been measuring the exhaust point not the tdc at compression

In any case I still can't get the 0.05mm gauge which is the smallest I have between the gap. It must be set to 0 or in between 0.03.

That said the bike runs fine. It doesn't help that I didn't take the carbs off and I have some non-oem large car coils on the front of the frame which make measuring the valve clearance that much more of a nuisance.

Oh and thank you for the help much appreciated.

 

[koolio]

Sorry to hijack this thread, I'm setting the valves on the other CB500t, while I'm there is there anyway to check the wear on the cam followers? Difficult to see from the front and the rear. Do the side panels where you adjust the valves safely come off?

 

[66Sprint]

Those "oddly" shaped "side-panels" are the cams' bearings, so NO, they don't "safely" come off.... They can be removed one at a time and re-installed IF you know/understand the engine well, but it's not a recommended proceedure as it CAN allow timing chain "jumps"....

 

[nigelrharris03]

Sorry to hijack this thread, I'm setting the valves on the other CB500t, while I'm there is there anyway to check the wear on the cam followers? Difficult to see from the front and the rear. Do the side panels where you adjust the valves safely come off?

The side panels are also the bearing housings. So removing these will cause the cam shaft to be unsupported. Also although it can be done they are not so easy to get back.
The best way to inspect the cam lobes is to turn the engine over slowly by the rotor nut and inspect the lobe surfaces whilst doing this.
The alternative is to remove the head and then the cams, but that does involve a lot more work.
Steve you got me again :lol: :lol: :lol: :lol:

 

[koolio]

Ok, nice to have you guys around neither Clymer, Haynes or the Original Workshop manual gives such warning!

 

[koolio]

Right, does anyone have any idea how you shift a frozen valve adjuster screw?

I've managed to get the lock nut off, but the screw is completely rusted locked, I've applied ACF-50/penetrating oil and tapped with a hammer. May pull out the blow torch tomorrow.

Also one of the valves adjuster screws has rusted together with the lock nut, so adjustment is with the lock nut only, I'm afraid of trying to rotate the lock nut more to open as it drags the valve adjuster with it.

 

[XTOP20A]

Right, does anyone have any idea how you shift a frozen valve adjuster screw?

I've managed to get the lock nut off, but the screw is completely rusted locked, I've applied ACF-50/penetrating oil and tapped with a hammer. May pull out the blow torch tomorrow.

Also one of the valves adjuster screws has rusted together with the lock nut, so adjustment is with the lock nut only, I'm afraid of trying to rotate the lock nut more to open as it drags the valve adjuster with it.

yes you need heat
but only concentrated heat for a very short period of time
you dont want to heat up any other bits,exspecially valve springs,you will ruin them in a very short time
this is when the fine concentrated heat from a small tip of an acetylene torch is quite usefull
all that said dont get anything hotter than smoking hot, 450 f tops
you start getting things red-hot you may as well scrap them

 

[66Sprint]

On the 450's/500T's, the valve adjustment excentric should have zero valve-spring or cam pressure against it when being adjusted...
Usually the problem is it tries to rotate as you tighten the locknut because of the lack of pressure.....
However, there IS an o-ring on the end of the excentric just beneth the journal block that can/does harden and prevent easy rotation sometimes...Not to mention the galvanic corrosion between the steel and aluminum...
Getting penetrant on that o-ring can swell it making the job harder.....
The "fix" is fairly involved and more easily discussed over the phone.....************...Steve

 

[koolio]

Steve, I'd really appreciate that. It'll have to be tomorrow.

I take it you are in Eastern Time, whats a good time to call?

 

[66Sprint]

Yes, Eastern time...... anytime after 0800.....

 

[koolio]

I've got the blow torch waiting next to the bike, but I thought I'd give it another crack with some proper penetrating oil which I'm going to get tomorrow.

Steve I was very busy today, but if you don't mind I'll give you a shout on the weekend or maybe next week.